What if you’re one of those “Real Housewives Of…” ladies, enjoy cocktails but have to watch every calorie (the camera adds 10 pounds)? With a typical four-ounce Margarita weighing in at 500 calories (the majority due to sugar in the liqueur or the cocktail mix), what’s a housewife do?

If you’re Bethenny Frankel, one of the Real Housewives Of New York (and a natural foods chef), you formulate a lower-calorie Margarita in an episode of your reality series. Then, when the most-asked quesiton on the entire Bravo website is “How to make a Skinny Girl Margarita,” you bottle it and sell it (find locations).

The open-and-serve bottled Margarita is all natural, made of 100% blue agave tequila, flavored with lime juice and sweetened with lower-glycemic agave syrup.

• First we added a packet of non-caloric sweetener. A liquid sweetener would have been better because a white sediment from the fillers in non-caloric sweetener settled at the bottom of the glass. But we really liked the added sweetness and didn’t mind the sediment.

• Next we tried adding more agave syrup. Ms. Frankel might have done the same, but for the desire to keep the cocktail to 100 calories/serving. Agave is a great, low-glycemic sweetener (it has an average glycemic index of 32, half that of sugar). While agave has the same calories as sugar (about 17 calories/teaspoon), it is 1.5 times sweeter—so your calories buy you more. You can spare it: Add another teaspoon of agave to Skinnygirl.